Vacuum-deposited organic photodetectors utilizing non-fullerene acceptors for enhanced detectivity in the green visible light spectrum

Boron subphthalocyanine (SubPc) is a small molecule active material that absorbs visible light efficiently at wavelengths ranging from 500 to 600 nm. Recent studies have demonstrated that blending SubPc and C60 (fullerene) as the active layer in organic photodetectors (OPDs) results in a high dark current and decreases detectivity. Moreover, N,N '-bis(naphthalen-1-yl)-N,N '-bis(phenyl)benzidine (NPB) can be employed as a blocking layer and as a donor on the active layer. In this study, the performance of OPDs is investigated using non-fullerene (NPB : SubPc) and fullerene (SubPc : C60) active layers. The OPD utilizing a non-fullerene-based device (NPB : SubPc) with a ratio of 1 : 3 exhibits high performance across various parameters. It demonstrated a low dark current density of 1.32 x 10-9 A cm-2, an external quantum efficiency (EQE) of 51.85%, a responsivity of 0.22 A W-1, and a high detectivity of 1.07 x 1013 Jones at a wavelength of 530 nm. Moreover, the device showed a linear dynamic range (LDR) of 109.29 dB, a frequency cut-off of 263.04 kHz, and a transient photovoltage in formed rise and fall times of 2.74 mu s and 1.51 mu s, respectively. These findings suggest that the developed device could be suitable for future fingerprint recognition, owing to its ability to detect visible green light. Herein, free fullerene and fullerene-based active layers are compared. NPB : SubPc exhibits higher detectivity than SubPc : C60 in the green selectivity. Thereby, free fullerene organic photodetectors are promising for efficient optical sensors.